The invention relates to a method for controlling a crop separating process of a combine harvester having a separation device from which the crop is transferred to a cleaning device, the cleaning device comprising at least one sieve with adjustable width that is driven in an oscillating manner to separate the grain from non-grain components, and a fan that creates an air flow to act upon the at least one sieve (15, 16) to loosen the crop located thereon, wherein substantially three different loosening phases (F, S, W) occur during the loosening of the crop, and a combine harvester for implementing the method.
A method for controlling a crop separating process of a combine harvester is disclosed by EP 0 728 409. In the known method, a plurality of so-called separation sensors is assigned to (grain) separating units of the harvesting machine designed as separating sieves, on the underside thereof. The separation sensors generate measured values during operation of the harvesting machine that depend on the quantity of crop separated out. The measured values are used in an evaluation unit to determine an actual separation curve. The actual separation curve that is determined is compared with an ideal separation curve in order to change the fan speed depending on deviations that occur between the separation curves. The method seeks to match the actual separation curve to the ideal separation curve.
A disadvantage of the method has proven to be that it is based on a purely mathematical model that accounts for changing harvesting conditions to a limited extent on the basis of a change made to individual coefficients of the mathematical model by the operator of the combine harvester. With respect to setting the fan speed, the method is based on an initially established ideal separation curve that can be changed only to a slight extent, and which requires further-reaching knowledge on the part of the operator in order to implement said adaptation of the mathematical model in a meaningful manner.